Operation limiting device for machine tool

ABSTRACT

An operation limiting device applicable to a wide variety of machine tools and which improves the freedom of setting an operation limiting area. Two or three drive axes (Xa, Za) in different directions are designated from among a plurality of drive axes in the machine tool and the designated drive axes (Xa, Za) form the two or three dimensional coordinate system. An area (Ar) for limiting the operation of the mobile body is set in the two or three dimensional coordinate system. A drive axis (Xa) which is in operation is determined, and in the two or three coordinate system including the drive axis which is in operation the operation of the mobile body is limited when the mobile body enters into the limiting area (Ar).

TECHNICAL FIELD

The present invention relates to an operation limiting device for amachine tool.

BACKGROUND ART

In the machine tool, in order to prevent the tool from interfering withother parts, the operation of the tool may be limited. For example, JPPatent Publication No. 60-160407 and JP Patent Publication No.2008-234295 disclose that the limit (minimum and maximum values) in amoving axis direction is set and when the tool movement exceeds thelimit value in manual machining operation, the manual operation isstopped.

Further, according to JP H4-71202 B2, by setting a workpieceinterference region corresponding to the position of the outer surfaceof the workpiece, whether or not a tool is entered into the workpieceinterference region is detected.

SUMMARY OF INVENTION Technical Problem(s)

However, in order to have a wide variety of functions, a machine toolhaving a number of drive axes has been proposed. For example, thereexists a drive axis used exclusively for truing a tool in addition to adrive axis used for moving the tool. Therefore, depending on the type ofthe mobile body and the type of the drive axis by which the mobile bodyis driven, condition of the interference state is different. Further,when the mobile body is operated by a plurality of drive axes, even themaximum and minimum values of operation limiting area relative to one ofthe plurality of the drive axes can be set, such limiting area is notconsidered to be appropriately set.

The present invention has been made in consideration with the aboveissues and the object of the invention is to provide an operationlimiting device for a machine tool which is applicable to a wide varietyof machine tools and yet which improves the degree of freedom in settingthe operation limiting region therefor.

Solution to Problem(s)

The present disclosure is characterized in that the operation limitingdevice for a machine tool includes a drive axis designating means fordesignating two or three drive axes in different directions among aplurality of drive axes, a coordinate system forming means for forming atwo-dimensional coordinate system or a three-dimensional coordinatesystem by the two or three drive axes designated by the drive axisdesignating means, a limiting area setting means for setting a limitingarea to limit an operation of a mobile body which moves by the two orthree drive axes designated by the drive axis designating means in thetwo-dimensional coordinate system or the three-dimensional coordinatesystem, the limiting area corresponding to the two or three drive axesdesignated by the drive axis designating means, a determining means fordetermining a drive axis by which the mobile body is in operation and alimiting means for limiting the operation of the mobile body when themobile body enters into the limiting area, using the limiting area setin the two-dimensional coordinate system or the three-dimensionalcoordinate system formed by the drive axis by which the mobile body isin operation.

According to this structure of the invention, two or three drive axes indifferent directions among a plurality of drive axes are designated andan area where the operation of the mobile body is limited in thetwo-dimensional coordinate system or the three-dimensional coordinatesystem including the designated drive axis. Accordingly, the degree offreedom of setting the operation limiting area can be highly improved.Further, the operation limiting area can be set according to the driveaxes even for the machine tool having various types of the drive axesand accordingly, the operation limiting area can be surely andappropriately set.

Preferably, the determining means determines the drive axis by which themobile body is in operation in a manual operation mode and the limitingmeans limits the operation of the mobile body, using the limiting areaset in the two-dimensional system or the three-dimensional coordinatesystem formed by the drive axis by which the mobile body is in operationin the manual operation mode.

Further, preferably, the determining means determines the drive axis bywhich the mobile body is in operation in an automated operation mode andthe limiting means limits the operation of the mobile body using thelimiting area set in the two-dimensional coordinate system or thethree-dimensional coordinate system formed by the drive axis by whichthe mobile body is in operation in the automated operation mode.

The applicable operation mode is either the manual operation mode or theautomated operation mode. At the manual operation mode, a workeroperates the machine tool and accordingly, the worker is naturally staysin the vicinity of the machine tool for operation thereof and at theautomated operation mode, the worker operates the machine tool stayingin the vicinity of the machine tool for confirmation of the operation.Accordingly, the worker can operate by observing the operation of themachine tool at the above operation mode. Thus, by applying the abovemodes, an interference caused by a careless mistake (mistakes such as,in data setting, in handle magnification selection or in overridesetting) can be avoided.

Preferably, the limiting means changes a handle magnification to alimited magnification at a handle operation mode of the manual operationmode. Further, preferably, the limiting means changes an inching speedto a limited speed at an inching motion operation mode of the manualoperation mode.

Further, preferably, the limiting means changes a designated speed to alimited speed.

Still further, preferably, the limiting means slows down a speed of themobile body without stopping thereof when the mobile body enters intothe limiting area. As one method of limiting the operation, the mobilebody is not stopped but the speed thereof is slowed down. Accordingly,the operation limiting area can be set with a relatively large clearancedistance. In other words, it is not necessary to severely set theoperation limiting area at a borderline position of whether or not tointerfere and therefore setting can be easily made. Further, if themobile body should enter into the operation limiting area by a settingerror or the like, the speed of the mobile body is slowed down andaccordingly a worker can recognize such speed change of the mobile bodyto let the worker recognize the possibility of existing of settingerror.

Particularly, during the manual operation mode, sometimes it may bedesired to have the mobile body operate until to a position close to anobject or have the mobile body to be in contact with the object. Undersuch situation it is preferable to have the mobile body to be inoperable state. However, a heavy collision between the object and themobile body should be avoided. Such request can be responded by adaptingthis method.

Particularly, during the automated operation mode, when the mobile bodyenters into the operation limiting area, the speed of the mobile body islimited and therefore, a worker can determine whether the program datais incorrect or not and if determined to be incorrect, the machineoperation can be stopped. On the other hand, if determined that theprogram data is correct and that the mobile body is operated properlywithin the operation limiting area, the worker can surely observe thelimited operation of the mobile body.

In this case, it is preferable that the limiting means slows down thespeed of the mobile body without stopping thereof when a target positionof the mobile body is in the limiting area. Further, it is preferablethat the limiting means slows down the speed of the mobile body withoutstopping thereof when a current position of the mobile body is in thelimiting area. It is preferable that the machine tool includes aplurality of drive axes in a same direction, the coordinate systemforming means forms a two-dimensional coordinate system or athree-dimensional coordinate system for each of the plurality of driveaxes in the same direction, the limiting area setting means sets thelimiting areas respectively corresponding to the plurality of drive axesin the same direction. It is preferable that the limiting area is formedof a rectangular shape or a rectangular parallelepiped shape and thelimiting area setting means sets the limiting area by designatingvertices of the rectangular shape or the rectangular parallelepipedshape in the two-dimensional coordinate system or the three-dimensionalcoordinate system.

BRIEF EXPLANATION OF ATTACHED DRAWINGS

FIG. 1 is a plain view of a grinding machine according to an embodimentof the invention:

FIG. 2 is a detail explanation view of a first operation limiting areain FIG. 1:

FIG. 3 is a detail explanation view of a second operation limiting areain FIG. 1:

FIG. 4 is a block diagram of a control device in FIG. 1:

FIG. 5 is a flowchart showing a process of a limiting area settingprocessing portion of FIG. 4:

FIG. 6 is a flowchart of a process of a determining limiting portion inFIG. 4:

FIG. 7 is a flowchart of a speed limiting process in FIG. 6: and

FIG. 8 is a view indicating an operation limiting area of athree-dimensional coordinate system at the steps S7 through S9 in FIG.5.

EMBODIMENTS FOR IMPLEMENTING INVENTION

<Structure of Grinding Machine>

As an example of a grinding machine according to the embodiment agrinding head traverse type grinding machine will be explained. However,it is noted that the invention is not limited to the grinding headtraverse type grinding machine, but any other type grinding machine canbe applicable and any machine tool other than the grinding machine canbe applicable.

The grinding tool according to the embodiment will be explained withreference to FIG. 1. As shown in FIG. 1, the grinding machine 1 includesa bed 11 fixed on a floor and a main spindle 12 and a tailstock device13 which rotatably support a workpiece W fixed to the bed 11 at bothsides. Further, the grinding machine 1 includes a grinding head 14movable on the bed 11 in a Z-axis (Za) direction and an X-axis (Xa)direction, a grinding wheel 15 rotatably supported by the grinding head14 and a sizing device 16 which measures a diameter of the workpiece W.

Still further, the grinding machine 1 includes a truing device 17 whichis movable on the grinding head 14 in a Z-axis (Zb) direction and anX-axis (b) direction. The truing device 17 is used for forming thegrinding wheel 15. Further, the grinding machine 1 is provided with acontrol device 18 which controls rotation of the main spindle 12 and thegrinding wheel 15 and at the same time, controls position of thegrinding wheel 15 relative to the workpiece W and further controls thetruing device 17. It is noted that the operation limiting deviceaccording to the invention corresponds to the control device 18.

(Explanation of Operation Limiting Area)

In the grinding machine 1, as indicated by the broken line in FIG. 1,the operation limiting areas Ar_((Xa-Za)) and Ar_((Xb-Zb)) are set.Detailed operation limiting areas Ar_((Xa-Za)) and Ar_((Xb-Zb)) will beexplained with reference to FIGS. 2 and 3.

The first operation limiting area Ar_((Xa-Za)) defines the interferencebetween the grinding wheel 15 and the workpiece W. In other words, asshown in FIG. 1, the first operation limiting area Ar_((Xa-Za))indicates a limiting area of a grinding point P_((Xa-Za)) of thegrinding wheel 15 relative to the workpiece W.

The grinding wheel 15 is operated by the drive axis in the Xa directionand the drive axis in the Za direction. Accordingly, the first operationlimiting area Ar_((Xa-Za)) is formed to be a rectangular shaped area inthe two-dimensional coordinate system formed by the Xa direction and theZa direction as shown in FIG. 1. In other words, the coordinate systemof the first operation limiting area Ar_((Xa-Za)) indicates atwo-dimensional coordinate system formed by the direction of movement ofthe grinding wheel 15 relative to the workpiece W defined as areference.

As shown in FIG. 2, the first operation limiting area Ar_((Xa-Za)) isenclosed by a reference point (Xa0, Za0), a first vertex (Xa1, Za1)which is separated from the reference point (Xa0, Za0) by ΔXa in an Xadirection, a second vertex (Xa2, Za2) which is separated from thereference point (Xa0, Za0) by ΔZa in Za direction and a third vertex(Xa3, Za3) which is separated from the second vertex (Xa2, Za2) by ΔXain the Xa direction to form a rectangular shape thereby.

The second operation limiting area Ar_((Xb-Zb)) defines the interferencebetween the tooling device 17 and the grinding wheel 15. In other words,as shown in FIG. 1, the second operation limiting area Ar_((Xb-Zb))indicates a limiting area of an end point P_((Xb-Zb)) of the truingdevice 17 relative to the grinding wheel 15.

The truing device 17 is operated by the drive axis in the Xb directionand the drive axis in the Zb direction. Accordingly, the secondoperation limiting area Ar_((Xb-Zb)) is formed to be a rectangular shapearea in the two-dimensional coordinate system formed by the Xb directionand the Zb direction as shown in FIG. 1. In other words, the coordinatesystem of the second operation limiting area Ar_((Xb-Zb)) indicates atwo-dimensional coordinate system formed by the direction of movement ofthe truing device 17 relative to the grinding wheel 15 defined as areference.

As shown in FIG. 3, the second operation limiting area Ar_((Xb-Zb)) isenclosed by a reference point (Xb0, Zb0), a first vertex (Xb1, Zb1)which is separated from the reference point (Xa0, Za0) by ΔXb in an Xbdirection, a second vertex (Xb2, Zb2) which is separated from thereference point (Xb0, Zb0) by ΔZb in Zb direction and a third vertex(Xb3, Zb3) which is separated from the second vertex (Xb2, Zb2) by ΔXbin the Xb direction to form a rectangular shape thereby.

(Block Diagram of Control Device)

Next, the functional block diagram for the control device 18 will beexplained with reference to FIG. 4. As shown in FIG. 4, the controldevice 18 includes an input control portion 101, an actuator controlportion 102, a limiting area setting portion 103, a limiting areamemorizing portion 104 and a determining control portion 105.

The input control portion 101 inputs an NC program by operation of aworker, obtains information memorized in an external media and obtainsoperation of the worker on an operation panel 300.

The actuator control portion 102 controls an actuator 200 such as motorbased on the NC program inputted by the input control portion 101. Forexample, when the workpiece W is machined by the grinding wheel 15, theactuator control portion 102 controls the grinding head 14 to move inthe Xa direction and the Za direction upon the instructions of the NCprogram. In this case, the actuator control portion 102 controls themotor which operates the grinding head 14.

Further, when the grinding wheel 15 is formed by operating the truingdevice 17, the actuator control portion 102 controls the truing device17 to move in the Xb direction and the Zb direction upon theinstructions of the NC program. In this case, the actuator controlportion 102 controls the motor which operates the truing device 17.Further, when the operation is limited by the determining controlportion 105, the actuator control portion 102 controls the speed of themobile body to be slowed down.

The limiting area setting portion 103 sets the first and the secondoperation limiting areas Ar_((Xa-Za)) and Ar_((Xb-Zb)) shown in FIGS. 1through 3. The limiting area setting portion 103 sets the first and thesecond operation limiting areas Ar_((Xa-Za)) and Ar_((Xb-Zb)) based onthe information relating to the limiting area inputted by the inputcontrol portion 101. The detail of the limiting area setting portion 103will be explained later.

The limiting area memorizing portion 104 memorizes the first and thesecond operation limiting areas Ar_((Xa-Za)) and Ar_((Xb-Zb)) which areset by the limiting area setting portion 103. It is noted however, thatthe first and the second operation limiting areas Ar_((Xa-Za)) andAr_((Xb-Zb)) which are memorized in the limiting area memorizing portion104 are the coordinate systems set as indicated in FIGS. 2 and 3 and thecoordinate of the vertices of the coordinate systems.

The determining control portion 105 determines whether an operationshould be limited or not when an operation limiting invalidation signalis OFF at the manual operation mode or the automated operation mode.When the determining control portion 105 determines that the operationshould be limited, the determining control portion 105 controls theactuator control portion 102 to slow down the speed of the mobile body.The operation limiting invalidation signal is obtained by the inputcontrol portion 101. The detail of the determining control portion 105will be explained later.

(Operation Limiting Area Setting Processing)

The processing for setting the operation limiting area by the limitingarea setting portion 103 will be explained with reference to FIG. 5. Asshown in FIG. 5, the limiting area setting portion 103 designates theaxes of the coordinate system for the operation limiting area (step S1)(corresponding to the drive axis designating means according to theinvention). For example, when the first operation limiting areaAr_((Xa-Za)) as shown in FIG. 1 and FIG. 2 is set, the two axes, theaxis Xa and the axis Za are designated. The drive axes to be designatedare inputted by a worker from the operation panel 300 in advance or maybe inputted using the drive axes memorized in the external media.Further, such drive axes can be described in the NC program.

Then, whether the number of the designated axes is “two (2)” or not isdetermined (at the step S2). If the number thereof is determined not tobe “two”, whether the number of the designated axis is three (3)” or notis determined (S6). If not the “three” (S6: N), the setting process isinvalidated and the process ends (S10). It is noted however, that at thestep S6, if the number of designated axis is not “three”, the programmay return to the step S1 to again designate the number of the axes atthe step S1.

At the step S2, when the number of designated axes is determined to bethe “two” (S2: Y), the two-dimensional coordinate system (A-B) is formedand the reference coordinate (A0, B0) in the two-dimensional coordinatesystem (A-B) is designated (S3) (corresponding to the coordinate systemforming means according to the invention). The coordinate system in FIG.2 is indicated as the two-dimensional coordinate system (Xa-Za) and thereference coordinate thereof is (Xa0, Za0). Inputting of the referencecoordinates (A0, B0) can be made by either one of NC program, externalmedia and the operation panel 300.

Next, the differences ΔA, ΔB from the reference coordinate (A0, B0) aredesignated (S4). In FIG. 2, the difference in the Xa axis direction isdesignated as ΔXa and the difference in the Za axis direction is ΔZa.Inputting of the differences ΔA, ΔB may be made similarly as explainedabove. Further, when the workpiece W is changed, the referencecoordinates (A0, B0) and the differences ΔA, ΔB may be designated byactivating the NC program in order to facilitate the inputting work bythe worker.

Then, the four vertex coordinates of the rectangular operation limitingarea Ar are calculated based on the reference coordinate (A0, B0) andthe differences ΔA, ΔB and are memorized in the limiting area memorizingportion 104 (S5) (corresponding to the limiting area setting meansaccording to the invention). In FIG. 2, the four vertexes of theoperation limiting area Ar_((Xa-Za)) are designated as four coordinates(Xa0, Za0), (Xa1, Za1), (Xa2, Za2) and (Xa3, Za3).

On the other hand, at the step S6, when the number of the designatedaxes is judged to be “three” (S6: Y), the three-dimensional coordinatesystem (D-E-F) is formed and the reference coordinate (D0, E0, F0) inthe three-dimensional coordinate system (D-E-F) is designated (S7)(corresponding to the coordinate system forming means according to theinvention). This will be explained, for example, with reference to FIG.8. Next, the differences ΔD, ΔE, ΔF from the reference coordinate (D0,E0, F0) in the coordinate axes are designated (S8). In FIG. 8, thedifference in the D-axis direction is designated as ΔD, the differencein the E-axis direction is ΔE and the difference in the F-axis directionis ΔF.

Then, the eight vertex coordinates of the rectangular parallelepipedoperation limiting area Ar are calculated based on the referencecoordinates (D0, E0, F0) and the differences ΔD, ΔE ΔF and are memorizedin the limiting area memorizing portion 104 (S9) (corresponding to thelimiting area setting means according to the invention). In FIG. 8, thevertexes of the operation limiting area Ar_((D-E-F)) are designated aseight coordinates (D0, E0, F0), (D1, E1, F1), (D2, E2, F2), (D3, E3,F3), (D4, E4, F4), (D5, E5, F5), (D6, E6, F6), and (D7, E7, F7).

Thus, two or three drive axes in different directions among theplurality of the drive axes are designated and the area in which theoperation of the mobile body is limited in the two-dimensionalcoordinate system or the three-dimensional coordinate system includingthe designated drive axes are set. Accordingly, the freedom of designfor setting the operation limiting area can be highly improved. Further,as explained above, even in a machine tool which includes a wide varietyof drive axes including such as Xb axis and Zb axis which move thetruing device 17 other than the axes such as Xa axis and Za axis whichmove the grinding head 14, an operation limiting area according to thetype of drive axes can be set to achieve a sure and proper setting ofthe operation limiting area.

(Operation Limiting Determining and Operation Limiting ControlProcessing)

Next, the operation limiting determining and the operation limitingcontrol processing by the operation limiting control portion 105 in FIG.4 will be explained with reference to FIGS. 6 and 7. The operationlimiting control portion 105 determines whether the operation mode is inmanual operation mode or in automated operation mode (S11)(Corresponding to the determining means according to the invention).

The manual operation mode includes a handle operation mode and theinching operation mode. The handle operation mode means the mode inwhich a handle provided at the operation panel 300 is, for example,rotated to move the designated mobile body in the designated axialdirection. In this handle operation mode, setting of the magnificationof the handle operation can be possible and accordingly, the mobile bodycan be moved with a speed corresponding to the set value of themagnified ratio of the handle operation.

The inching operation mode means the mode in which an inching buttonwhich is provided at the operation panel 300 is pushed down to move thedesignated mobile body in the designated axial direction. The worker canset an overriding of the inching speed by operating the operation panel300.

Next, at the step S11, whether the operation limiting invalidationsignal is OFF or not is determined (S12) when the mode is under themanual operation mode or the automated operation mode (S11: Y). At theinitial setting of the operation limiting invalidation signal is set tobe OFF where the operation limiting is to be performed. An ON/OFFswitching-over control of the operation limiting invalidation signal canbe freely made by a worker using the operation panel 300 (See FIG. 4).

Next, at the step S12, when the operation limiting invalidation signalis determined to be OFF (S12: Y), whether a coordinate system formed bydrive axis which is going to operate to move the mobile body towards thetarget position or the drive axis which is currently operating (theseaxes are called hereinafter as an “operating axis”) exists among thecoordinate systems memorized in the limiting area memorizing portion 104or not is determined (S13). (Corresponding to the determining meansaccording to the invention). For example, when the operating axiscorresponds to the Xa axis, a two-dimensional coordinate system (Xa-Za)exists.

Next, at the step S13, an appropriate coordinate system is determined tobe existing (S13: Y), then whether the target position or the currentposition of the subject position P of the mobile body exists in theoperation limiting area or not is determined (S14). For example, asshown in FIG. 1, the grinding point P_((Xa-Za)) of the grinding wheelwhich corresponds to the subject point P is in the operation limitingarea Ar_((Xa-Za)) or not is determined.

Next, when the condition of the step S14 is satisfied, the speedlimiting control is performed (S15). (Corresponding to the limitingmeans according to the invention). On the other hand, when theconditions of the steps S11 through S14 are not satisfied, a normalcontrol is performed (S16). The normal control means a control that thespeed limiting control at the step S15 is not operated.

It is noted here that at the step S12, when the operation limitinginvalidation signal is changed to ON by the operation of a worker, thenormal control is performed as explained above. When a correct normaloperation is confirmed during the normal controlling, it is possible tokeep the operation limiting validation signal to be ON. While theoperation limiting validation signal keeps ON state, no speed limitingcontrol is performed and normal control is performed.

The speed limiting control will be explained hereinafter, with referenceto FIG. 7. The mode for performing the speed limiting control from thestep S11 in FIG. 6 is in the handle operation mode, the inchingoperation mode or the automated operation mode.

As shown in FIG. 7, when the mode is the handle operation mode (S21: Y),whether the current handle magnification is greater than a predeterminedlimiting magnification or not is determined. (S22). If determination issatisfied (Yes), the handle magnification is changed to the limitingmagnification. In other words, thereafter, the mobile body is operatedunder the limiting magnification set lower than the handlemagnification. It is noted that the limiting magnification is set to bea value lower than the magnification normally set, but not includingzero.

When the mode is in the inching operation mode (S21: N, S24: Y), whetherthe currently set inching speed is greater than a predetermined limitingspeed or not is determined (S25). If determination is satisfied (Yes),the inching speed is changed to the limiting speed. In other words,thereafter, the mobile body is operated under the limiting speed setlower than the inching speed. It is noted that the limiting speed is setto be a value lower than normally set, but not including zero.

When the mode is in the automated operation mode (S24: N, S27: Y),whether the target speed or a current designated speed is greater than apredetermined limiting speed or not is determined (S28). If judgment issatisfied (Yes), the designated speed is changed to the limiting speed.In other words, thereafter, the mobile body is operated under thelimiting speed set lower than the designated speed. It is noted that thelimiting speed is set to be a value lower than normally set, but notincluding zero.

As explained above, the mode for operation limiting is applied in themanual operation mode or the automated operation mode. In the manualoperation mode, the operation is performed by a worker and therefore,the worker naturally stays in the vicinity of the machine tool. At theautomated operation mode, the operation is performed under the workerstaying in the vicinity of the machine tool, confirming the operation.Thus, by applying the operation limiting to the above modes, aninterference caused by a careless mistake (mistakes such as, in datasetting, in handle magnification selection or in override setting) canbe avoided.

As one method of limiting the operation, the mobile body is not stoppedbut the speed thereof is slowed down. Accordingly, the operationlimiting area Ar can be set with a relatively a large clearancedistance. In other words, it is not necessary to set the operationlimiting area Ar at a borderline position of whether or not for themobile body to interfere with the object and therefore setting can beeasily made. Further, if the mobile body should enter into the operationlimiting area by a setting error or the like, the speed of the mobilebody is slowed down and accordingly a worker can recognize such speedchange of the mobile body to let the worker know the possibility ofexisting of setting error

Further, particularly, during the manual operation mode, sometimes itmay be desired to have the mobile body operate until to a position closeto an object or have the mobile body to be in contact with the object.Under such situation it is preferable to have the mobile body to be inoperable state. However, a heavy collision between the object and themobile body should be avoided. Such request can be responded by adaptingthis method according to the embodiment.

Particularly, during the automated operation mode, when the mobile bodyenters into the operation limiting area, the speed of the mobile body islimited and therefore, a worker can determine whether the program datais wrong or not and if the worker judges that the program data isincorrect, the machine operation can be stopped, for example, by anemergency button being pushed by the worker while the speed of themobile body is decreased. On the other hand, if determined that theprogram data is correct and that the mobile body is operated properlywithin the operation limiting area, the worker can surely observe thelimited operation of the mobile body. It is noted that the emergencystopping operation of the machine is performed separately from theprocessing of the operation limiting determining and the operationlimiting control processing.

According to the embodiment, as one of the operation limiting methods,the speed of the mobile body is slowed down not to stop the movement ofthe mobile body. However, the method is not limited to this embodimentbut can be stopping the mobile body. Such stopping of the mobile bodywould not obtain the effects which are obtained by not stopping themobile body.

The invention claimed is:
 1. An operation limiting device for a machinetool comprising: input control means; a drive axis designating means formanually designating two or three first drive axes and two or threesecond drive axes among a plurality of drive axes of the machine toolusing the input control means; a coordinate system forming means forforming a first two-dimensional coordinate system or a firstthree-dimensional coordinate system by the two or three first drive axesdesignated by the drive axis designating means, and for forming a secondtwo-dimensional coordinate system or a second three-dimensionalcoordinate system by the two or three second drive axes designated bythe two or three second drive axes designated by the drive axisdesignating means, wherein at least one of the two second drive axesextends in a direction that is different from either of the two firstdrive axes; a limiting area setting means for setting a first limitingarea based on information relating to the first limiting area manuallyinput by the input control means to limit an operation of a first mobilebody which moves according to the two or three first drive axesdesignated by the drive axis designating means in the firsttwo-dimensional coordinate system or the first three-dimensionalcoordinate system, the first limiting area corresponding to the two orthree first drive axes designated by the drive axis designating means,the limiting area setting means for setting a second limiting area basedon information relating to the second limiting area manually input bythe input control means to limit an operation of a second mobile bodywhich moves according to the two or three second drive axes designatedby the drive axis designating means in the second two dimensionalcoordinate system or the second three-dimensional coordinate system, thesecond limiting area corresponding to the two or three second drive axesdesignated by the drive axis designating means; a determining means fordetermining two or three third drive axes by which the first mobile bodyor the second mobile body is in operation and determining whether athird two-coordinate system or a third three-coordinate system formed bythe third drive axes is one of (a1) the first two-dimensional coordinatesystem or the first three-dimensional coordinate system and (a2) thesecond two dimensional coordinate system or the second three-dimensionalcoordinate system; and a limiting means for limiting the operation ofthe first mobile body or the second mobile body when the respectivemobile body enters into the third limiting area, wherein: the firstcoordinate system has a same components as the first drive axes; thesecond coordinate system has a same components as the second drive axes;the two or three first drive axes move the first mobile body withrespect to a bed of the machine tool; the two or three second drive axesmove the second mobile body with respect to the first mobile body; thefirst limiting area limits an operation of the first mobile body whichmoves according to the two or three first drive axes; and the secondlimiting area limits an operation of the second mobile body which movesaccording to the two or three second drive axes.
 2. The operationlimiting device for a machine tool according to claim 1, wherein thedetermining means determines the drive axis by which the mobile body isin operation in a manual operation mode and the limiting means limitsthe operation of the mobile body using the limiting area set in thetwo-dimensional coordinate system or the three-dimensional coordinatesystem formed by the drive axis by which the mobile body is in operationin the manual operation mode.
 3. The operation limiting device for amachine tool according to claim 2, wherein the limiting means changes ahandle magnification to a limited magnification at a handle operationmode in the manual operation mode.
 4. The operation limiting device fora machine tool according to claim 2, wherein the limiting means changesan inching speed to a limited speed at an inching motion operation modein the manual operation mode.
 5. The operation limiting device for amachine tool according to claim 1, wherein the determining meansdetermines the drive axis by which the mobile body is in operation in anautomated operation mode and the limiting means limits the operation ofthe mobile body using the limiting area set in the two-dimensionalcoordinate system or the three-dimensional coordinate system formed bythe drive axis by which the mobile body is in operation in the automatedoperation mode.
 6. The operation limiting device for a machine toolaccording to claim 5, wherein the limiting means changes a designatedspeed to a limited speed.
 7. The operation limiting device for a machinetool according to claim 2, wherein the limiting means slows down a speedof the mobile body without stopping thereof when the mobile body entersinto the limiting area.
 8. The operation limiting device for a machinetool according to claim 7, wherein the limiting means slows down thespeed of the mobile body without stopping thereof when a target positionof the mobile body is in the limiting area.
 9. The operation limitingdevice for a machine tool according to claim 7, the limiting means slowsdown the speed of the mobile body without stopping thereof when acurrent position of the mobile body is in the limiting area.
 10. Theoperation limiting device for a machine tool according to claim 1,wherein the machine tool includes a plurality of drive axes in a samedirection, the coordinate system forming means forms a two-dimensionalcoordinate system or a three-dimensional coordinate system for each ofthe plurality of drive axes in the same direction, and wherein thelimiting area setting means sets the limiting areas respectivelycorresponding to the plurality of drive axes in the same direction. 11.The operation limiting device for a machine tool according to claim 1,the plurality of limiting areas are each formed of a rectangular shapeor a rectangular parallelepiped shape and the limiting area settingmeans sets the limiting areas by designating vertices of the rectangularshape or the rectangular parallelepiped shape in the two-dimensionalcoordinate system or the three-dimensional coordinate system.